L. Franco

Review: Copper and inflammation — a possible rationale for the pharmalogical manipulation of inflammatory discorders

Acute and chronic inflammations are characterized, among other features, by changes in the metabolism of copper and by a widespread responsiveness to the therapy with copper-containing molecules.The exact map of inflammation-induced copper movements as well as the role played by the metal in the pathogenesis of inflammatory disorders are, however, far from being clear, and this is especially true in the case of chronic processes.Nevertheless the present knowledge suggests that the ‘copper approach’ may provide a new way for coping with the problem of anti-inflammatory/anti-arthritic therapies. The administration of exogenous copper, and thein vivo manipulation of the endogenous metal levels are proposed as two possible therapeutic strategies, not necessarily mutually exclusive.For a better understanding of the value of such an approach, further research work is needed, especially to attain a more detailed know-how on the involved chemical forms, distribution and functions of copper in both normal as well as inflamed organisms.

Expression of COX-1, COX-2, and inducible nitric oxide synthase protein in human gastric antrum with Helicobacter pylori infection.

For a better understanding of the regulation of prostaglandin and nitric oxide (NO) synthesis in circumstances in which the gastric mucosa is inflamed, we have examined the ex vivo production of NO and prostaglandin E2 and the protein expression of inducible nitric oxide synthase (iNOS) and 2 cyclo-oxygenase (COX) isoforms in gastric biopsies from nine Helicobacter pylori-infected patients with active gastritis and six Helicobacter pylori (HP)-negative patients. The results indicate a significant increased of NO and PGE2 in patients with HP infection compared with uninfected samples. These findings were paralleled by marked increases in iNOS and in COX-1 and COX-2 protein expression. Expression of iNOS and COX-2 protein was absent in the mucosa of HP-negative controls. We have demonstrated that iNOS protein is expressed in the gastric mucosa of patients with HP infection. It is likely that iNOS expression and the corresponding high release of NO may play an important role in gastric inflammation associated with HP infection. However, the expression of COX-1 and COX-2 and the parallel increase of prostaglandin E2 could imply that these factors could limit the extend of mucosal damage. In previous reports NO has been shown to stimulate the COX activity, so we think that the role of NO could be both in the regulation of normal function and in the genesis of diseases.

Copper metabolism during acute inflammation: studies on liver and serum copper concentrations in normal and inflamed rats

1 The concentration of copper in serum and liver was determined by atomic absorption spectrophotometry in a study performed on normal rats of either sex and in female rats with carrageenan‐induced pleurisy. 2 In the normal animal, total serum copper concentration is significantly higher in female rats, and appears to be higher in mature animals in females. 3 In normal rats of either sex, liver copper concentration undergoes daily variations which are inversely related to the weight of the organ and which leave constant the total amount of metal in the liver. Moreover a day to day non‐cyclic variability of liver copper concentration and liver weight was observed. 4 This first set of data showed that comparison with time control was essential. 5 In the inflamed rat, a significant rise of total serum copper at 22, 48 and 72 h after the induction of inflammation was observed. From 96 h up to 240 h post‐injection no significant differences were evident. 6 Total liver copper content did not change in the inflamed rats. 7 During acute inflammation in the rat, the copper needed for the increased synthesis of caeruloplasmin is supplied without depletion of liver copper stores.

Copper and zinc status during acute inflammation: studies on blood, liver and kidneys metal levels in normal and inflamed rats

The concentrations of copper and zinc in plasma, blood cells, liver and kidneys were determined in a study performed on normal female rats, and in female rats with carrageenan induced pleurisy. In the normal rat, the total amount of both metals increases, from 51 to 79 days of age, in all the compartments examined. This increase was mostly, and in some case exclusively, dependent upon the growth of the animal, although high individual and day to day variations in both copper and zinc values were observed in all the compartments studied. In the blood of inflamed rats a statistically significant increase in copper was measured during the crucial hours of the experiment (i.e. from 6 to 72 h); over 90% of the increase found was attributable to variations in plasma copper concentration values. In the liver of inflamed rats a statistically significant increase in zinc was measured at 6, 22 and 48 h after the carrageenan injection. The induction of the acute non-infective inflammatory process did not cause quantitative changes of both copper and zinc in all the other compartments considered in the present study. These results seem to suggest that, during acute inflammation, the organism increases its requirement for copper and zinc, and that this demand is fulfilled by enhanced intestinal absorption and/or decreased intestinal excretion of both metals.

Nitric oxide enhances prostaglandin production in ethanol-induced gastric mucosal injury in rats.

The interaction between endogenous nitric oxide (NO), elicited by administration of Escherichia coli lipopolysaccharide, and cyclooxygenase system, in ethanol-induced injury in rat gastric mucosa, was investigated. Administration of graded doses of lipopolysaccharide reduced the gastric mucosal injury in response to ethanol. The ex vivo production of both nitrite and prostaglandin E2 was increased in dose-related manner by lipopolysaccharide. Pretreatment with dexamethasone, L-N6-(1-Iminoethyl)lysine(dihydrochloride) and L-NG-nitro arginine methyl ester inhibited the protection associated with lipopolysaccharide treatment and the ex vivo production of both, nitrite and prostaglandin E2. The pretreatment with L-arginine counteracted the decrease of nitrite and prostaglandin E2 production in lipopolysaccharide-treated rats in which nitric oxide synthesis was blocked by L-N6-(1-Iminoethyl)lysine(dihydrochloride). Administration of sodium nitroprusside and S-nitroso-N-acetyl-D,L-penicillamine caused a dose related enhancement in the accumulation of prostaglandin E2. Indomethacin administration and N-(2-Cyclohexyloxy-4-nitrophenyl)methanesulfonamide were ineffective in suppressing lipopolysaccharide-mediated protection against ethanol-induced damage, and in suppressing ex vivo increase of nitrite whereas the ex vivo increase of prostaglandin E2 was prevented in a dose-related fashion. These results indicate that in ethanol-induced rat gastric injury, endogenous NO elicited by lipopolysaccharide or released by NO donors is able to activate the cyclooxygenase pathway, and the protective effect of lipopolysaccharide is dependent upon NO formation.

Serum copper and ceruloplasmin levels in rheumatoid arthritis and degenerative joint disease and their pharmacological implications

Serum copper concentration and ceruloplasmin activity were measured in patients with clinically established rheumatoid arthritis (R.A.) during the active phase, in patients with degenerative joint disease (D.J.D.) and in normal subjects. Copper and ceruloplasmin serum levels are significantly increased (P less than 0.01) in the arthritic group, but not in the degenerative joint disease group. Copper and ceruloplasmin levels are high significantly correlated in all the groups. This parallel enhancement of serum copper and ceruloplasmin in R.A. is commented in view of a possible protective role of endogenous copper and/or ceruloplasmin in inflammation.

PEG superoxide dismutase derivatives: anti-inflammatory activity in carrageenan pelurisy in rats.

Two derivatives of superoxide dismutase (SOD) with monomethoxypolyethyleneglycol, having different molecular weights (46,000 and 121,000 D) and different plasma half-lives are tested in carrageenan pleurisy in rats after single i.v. injection. The compounds were prepared following an original method where the polymer is activated by trichlorophenylchloroformate to give a phenylcarbonate which is reactive towards the protein amino groups. The anti-inflammatory activity of derivatives results correlated to their kinetics, lasting longer for the derivative with the longest half-life (SOD-PEG 18). SOD activity, in plasma of rats treated with SOD-PEG 18, is still present 24 hour after carrageenan, in agreement with the prolonged anti-inflammatory activity. Moreover SOD-PEG 18 diffuses well in pleural exudate, as it is evidentiated from the increase with time of exudate/plasma concentration ratio.

Synthesis and anti-inflammatory effects of some bis(2-benzimidazolyl)thioethers and their copper(II) chelates, orally administered to rats

Abstract A series of bis(2-benzimidazolyl)thioethers and their copper(II) chelates has been prepared and tested. All the ligands and copper(II) complexes synthesized were orally assayed in the rat for anti-inflammatory activity in both acute (carrageenan edema) and chronic (adjuvant arthritis) models of inflammation. Some compounds were also examined for gastric-irritancy potential. Among tested molecules, the copper complex with the unsubstituted lead structure (NSN) showed the best pharmacological activities, which seem to be dependent upon the presence and bioavailability of some intact complex in the gastrointestinal tract after oral administration. The compound did not exhibit any capacity to elicit significant lesion development of the gastric mucosa of stress-sensitized rats. Structure—activity relationships of the copper complexes are discussed.

Role of nitric oxide in prevention of ethanol-induced gastric damage by CuNSN a copper-chelating compound

CuNSN a bis (2-benzimidazolyl)thiother complex with copper, has been shown to prevent the formation of acute gastric mucosal lesions induced by acetylsalicylic acid and ethanol. In the present study we have investigated the role of NO in CuNSN protection from ethanol-induced gastric damage. For this purpose we have used the inhibitor of NO biosynthesis, NG-nitro-L-arginine (L-NNA) as well as L- or D-arginine. Gastric mucosal damage caused by ethanol was dose-dependently increased by i.v. administration of graded dose of L-NNA. The effect of L-NNA was completely antagonized by the administration of L-arginine while D-arginine did not cause a reduction in the damage. Treatment with CuNSN has shown a significant protection against the damage produced by ethanol. This protection was not reversed by L-NNA and was significant as compared to the corresponding control group. The combination of L-NNA plus L-arginine potentiates this protection. These results suggest that NO synthesis is not involved in the protection afforded by CuNSN.

Eicosanoid and gastroprotection by copper derivatives and NDGA.

We investigated the effect of oral administration of graded doses of: nordihydroguaiaretic acid (NDGA), CuNSN, a bis(2-benzimidazolyl)thioether and CuCl2 on ethanol-induced gastric damage in the rat and the role of leukotrienes and prostaglandins in attenuating this damage. In the experiments we determinedex-vivo eicosanoid release in the rat gastric mucosa pretreated with the above-mentioned compounds. The results indicate that the gastric lesion is accompanied by an increase in mucosa-synthesize LTC4, while PGE2 formation remains unchanged. Pretreatment with NDGA, CuNSN and CuCl2, protects the gastric mucosa from damages and reduces the increase in LTC4 mucosal formation. CuNSN and CuCl2 increase the PGE2 release, while NDGA has no effect on this pathway. These results suggest that one of the possible mechanisms of the NDGA protective effect is related to the inhibition of LTC4 formation, while the PGE2 increase in synthesis together with the leukotriene inhibition could contribute to the protective effect of CuNSN and CuCl2.